Gale Warning 564, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
514 PM AKDT Wed Aug 28 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today
through Friday)...

An upper level low currently over the southern tip of the Kenai
Peninsula will move slowly east over the next 36 hours while
dissipating. The widespread rain currently over the southern
Mainland will dissipate from west to east starting tonight. For
the Cook Inlet areas and Mat-Su, Thursday should be mostly dry,
but the region may begin the morning with low stratus and fog
blanketing the valleys. With the late August sun still having
some power to it, clouds may scatter out through the day, leading
to an overall pleasant day, hopefully. Areas to the east,
particularly from Valdez to Cordova will likely have some
lingering showers.

Starting Friday a low pressure system will move northeast from
the southeastern Gulf to south of the Sound. The track of the low
remains uncertain but the sensible weather other than the marine
wind field is fairly high confidence. Rain and easterly winds will
start off in Kodiak early Friday morning, moving north to the
western Prince William Sound/eastern Kenai Peninsula through the
day. Rain will be light to moderate, mostly along the coast with
upslope flow. Expect the rain to slide slowly east towards Valdez
and Cordova by Saturday, with chances of inland rain late Saturday
as the upper level low center reaches the southern Mainland.

-Jones

&&

.SHORT TERM FORECAST FOR SOUTHWEST ALASKA, THE BERING
SEA/ALEUTIANS (Days 1 through 3: This afternoon through
Saturday)...

A stacked low that had been drifting over Southwest this morning
is venturing farther east into Southcentral, but is still
imparting weak cyclonic flow over Southwest where swaths of low
clouds are still skirting the coastline into the northern AKPen.
Where skies have cleared out, scattered showers have quickly
filled in where partial solar heating has generated some weak low
level instability. By later tonight as conditions cool and
stabilize, areas of fog will likely fill back in over lower
elevations of Southwest, especially where it can stay clear enough
to radiate out and reach saturation near the surface. Farther
west, a gale force low continues to track across the far southern
Bering, with the center now moving just north of Adak. This will
be the main weather maker for the next couple days as it heads
generally east along the Aleutian Chain on it's way to the western
Gulf.

From late tonight into Thursday, the Bering low will intensify
just a bit as an upper level shortwave digging into the western
Bering merges with the upper level portion of the low. Gusty
easterly winds will flip around to northwesterly along the
Aleutian Chain as the low moves east and crosses to the Pacific
side on Thursday afternoon. Easterly winds and rain will meanwhile
progress up the AKPen throughout the day and into Thursday night
as the low approaches the western edge of the Gulf. Gusty east
winds will work a ways up into Bristol Bay on Friday as the low
fully exits into the Gulf, but most of the steady rain with this
system will stay south of the region, but scattered afternoon
showers will continue across Southwest both Thursday and Friday.
Winds will turn more northerly and weaken on Saturday as the low
continues farther east. Farther west across the Bering, a
shortwave trough will drop southeast late Friday into Saturday,
pushing scattered showers across the Pribilofs and into the
eastern Aleutians/AKPen.

-AS

&&

.LONG TERM FORECAST (Days 4 through 7: Sunday through Wednesday)...

The Alaska Weather Map continues under a broad upper level
cyclonic flow extending from Eastern Russia to the Canadian
Provinces. A moderately developed low center over the Southern
Alaska Peninsula swings into the Southern Gulf of Alaska, becoming
nearly stationary and forming a moderate amplitude trough through
midweek. A weaker low center South of Prince William Sound Sunday
dissipates into a trough over the Eastern Gulf of Alaska and
moves into Canada Monday. This pattern continues an energetic and
progressive pattern across the region, bringing locally stormy
conditions across the Southern portions of the state through the
forecast period. A well clustered model ensemble of the GFS/ECMWF/
Canadian products maintain good detail through Tuesday before
diverging in storm tracks. A second intensifying low approaches
the Western Bering for Wednesday morning.

With the low's movement along the Gulf coasts, generally direct
onshore flow spreads locally heavy rainfall into the coastal zones
across Kodiak Island into the AKPEN, and Northwards along the
Eastern slopes of the Alaska Range through Wednesday. The heavier
rainfall continues to migrate across the Eastern Kenai Peninsula
and Prince William Sound to the Canadian border. In the Far West,
another low center out of Eastern Russia and its front approaches
the Western Aleutians Tuesday. Gusty winds with the front
increases to gale force by Wednesday, as the front spreads from
the Western Aleutians for Wednesday. Locally heavy rains are
expected over the Western Aleutians and Bering Tuesday and
Wednesday.

-Kutz

&&

.AVIATION...

PANC...Periods of light rain and MVFR ceilings will persist
through at least late afternoon, with rain gradually tapering off
during the evening hours as an upper low exits to the east. With a
very moist airmass in place, this is an ideal environment for low
clouds (IFR/LIFR) and possibly fog to develop after rain ends.
It's always challenging to determine timing and exact ceiling/vis
in these scenarios. With light winds in the low levels low clouds
are favored over fog. Thus, the latest forecast indicates a trend
of lowering ceilings tonight with fog in the vicinity. Conditions
could end up being lower, but will first wait to see what develops
after rain ends. With a weak flow regime persisting on Thursday,
conditions will be slow to improve. Based on climatology, would
expect some lifting of ceilings by late morning/early afternoon.

&&